In connection with known air-conditioning systems, refrigeration or dehumidification at excessive inside temperatures is generated based on a refrigeration unit coupled with the driving engine of the motor vehicle, and, if the inside temperature is too low, heat is generated by switching on the heat exchanger, which is supplied by the cooling circulation of the driving engine of the motor vehicle and consequently with the off-heat of said engine. The inside temperature is controlled or regulated with such systems substantially through air-side adjustment by setting a mixed-air valve on the inlet of a mixing chamber, by which the ratio of admitted cold air to admitted hot air is variable, and/or with water-side adjustment through setting a valve, by which the feed of cooling fluid to the heat exchanger is variable, such fluid being heated by the off-heat of the engine of the motor vehicle. Such an air-conditioning system requires high energy and operating expenditure and can react to changing temperature conditions in the interior of the motor vehicle only sluggishly or not at all.
As compared to the above, a more rapid adaptation to different temperature conditions, combined at the same time with a substantially simplified operation and reduced energy expenditure can be accomplished according to the invention by virtue of the instruction of claim 1. Advantageous further developments of the invention are the subject matter of the subsidiary claims.
By using a refrigeration unit that is self-regulating or self-controlling independently of the driving engine of the motor vehicle, on the one hand, and a separate controllable useful heat source that is consequently independent of the amount of off-heat of the cooling medium of the driving engine, it is possible to rapidly adapt the system to the temperature of the interior space with only the absolutely required expenditure of energy and also in a very simple way due to the adjustment connection between the refrigeration unit and the useful heat source, using only one single temperature regulator.
The above-described motor vehicle air-conditioning system with a regulating range of the useful heat source adapted to the regulating range of the refrigeration unit is especially suitable for vehicles without the usual air-side adjustment by means of a mixed-air valve and/or water-side adjustment of a heat exchanger supplied with off-heat of the cooling water of the motor drive of the motor vehicle, and thus particularly for air-conditioning systems operated without the exploitation of off-heat. When used for motor vehicles solely or partly driven by an internal combustion engine with a cooling water circulation through a heat exchanger in the air-conditioning system and air-side temperature adjustment by means of a mixed-air valve in a mixing space, into which fresh air can be admitted on the inlet side, on the one hand, and air heated by a heat exchanger supplied with cooling water, on the other hand, provision is made according to a preferred exemplified embodiment of the invention between the first regulating range and the last regulating range for an intermediate regulating range with air-side adjustment by at least one mixed-air valve in a mixing space and/or water-side adjustment by at least one valve in a heat exchanger supplied with off-heat.
The first regulating range preferably extends over 0 to 30% of the total regulating range of the single tempering adjustment means, and the regulating range of the useful heat source, if an intermediate regulating range is present with air-side or water-side adjustment, extends over a regulating range of 60 to 100% of the total regulating range of the single temperature regulator.